diff --git a/go/vehicle-gateway/internal/stats/daily_metric.go b/go/vehicle-gateway/internal/stats/daily_metric.go
index 5e37e461..9f9b2140 100644
--- a/go/vehicle-gateway/internal/stats/daily_metric.go
+++ b/go/vehicle-gateway/internal/stats/daily_metric.go
@@ -18,12 +18,14 @@ type Execer interface {
 }
 
 type Writer struct {
-	exec             Execer
-	query            Queryer
-	loc              *time.Location
-	mu               sync.Mutex
-	lastTotalMileage map[string]float64
-	baselineCache    map[string]sourceBaselineCacheEntry
+	exec                Execer
+	query               Queryer
+	loc                 *time.Location
+	sourceTouchInterval time.Duration
+	mu                  sync.Mutex
+	lastTotalMileage    map[string]float64
+	lastSourceSeen      map[string]time.Time
+	baselineCache       map[string]sourceBaselineCacheEntry
 }
 
 type MetricSample struct {
@@ -46,10 +48,12 @@ func NewWriter(exec Execer, loc *time.Location) *Writer {
 		loc = time.FixedZone("Asia/Shanghai", 8*3600)
 	}
 	writer := &Writer{
-		exec:             exec,
-		loc:              loc,
-		lastTotalMileage: map[string]float64{},
-		baselineCache:    map[string]sourceBaselineCacheEntry{},
+		exec:                exec,
+		loc:                 loc,
+		sourceTouchInterval: time.Minute,
+		lastTotalMileage:    map[string]float64{},
+		lastSourceSeen:      map[string]time.Time{},
+		baselineCache:       map[string]sourceBaselineCacheEntry{},
 	}
 	if query, ok := exec.(Queryer); ok {
 		writer.query = query
@@ -76,11 +80,20 @@ func (w *Writer) EnsureSchema(ctx context.Context) error {
 }
 
 func (w *Writer) Append(ctx context.Context, env envelope.FrameEnvelope) error {
+	identity, hasSource := NewSourceIdentity(env.Protocol, env.SourceEndpoint)
+	if hasSource {
+		seenAt := w.sourceSeenAt(env)
+		if w.shouldTouchSource(identity, seenAt) {
+			if err := UpsertDataSource(ctx, w.exec, identity, seenAt); err != nil {
+				return err
+			}
+			w.markSourceTouched(identity, seenAt)
+		}
+	}
 	samples, err := SamplesFromEnvelope(env, w.loc)
 	if err != nil {
 		return err
 	}
-	identity, hasSource := NewSourceIdentity(env.Protocol, env.SourceEndpoint)
 	for _, sample := range samples {
 		if w.seenSameMileage(sample) {
 			continue
@@ -88,9 +101,6 @@ func (w *Writer) Append(ctx context.Context, env envelope.FrameEnvelope) error {
 		if !hasSource {
 			continue
 		}
-		if err := UpsertDataSource(ctx, w.exec, identity, sample.EventTime); err != nil {
-			return err
-		}
 		candidate := SourceMileageSampleFromMetric(sample, identity)
 		if err := w.applyRealtimeBaseline(ctx, &candidate); err != nil {
 			return err
@@ -106,6 +116,35 @@ func (w *Writer) Append(ctx context.Context, env envelope.FrameEnvelope) error {
 	return nil
 }
 
+func (w *Writer) sourceSeenAt(env envelope.FrameEnvelope) time.Time {
+	eventMS := env.EventTimeMS
+	if eventMS <= 0 {
+		eventMS = env.ReceivedAtMS
+	}
+	if eventMS > 0 {
+		return time.UnixMilli(eventMS).In(w.loc)
+	}
+	return time.Now().In(w.loc)
+}
+
+func (w *Writer) shouldTouchSource(identity SourceIdentity, seenAt time.Time) bool {
+	key := string(identity.Protocol) + "|" + identity.SourceIP
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	last, ok := w.lastSourceSeen[key]
+	if ok && !seenAt.After(last.Add(w.sourceTouchInterval)) {
+		return false
+	}
+	return true
+}
+
+func (w *Writer) markSourceTouched(identity SourceIdentity, seenAt time.Time) {
+	key := string(identity.Protocol) + "|" + identity.SourceIP
+	w.mu.Lock()
+	w.lastSourceSeen[key] = seenAt
+	w.mu.Unlock()
+}
+
 func (w *Writer) seenSameMileage(sample MetricSample) bool {
 	key := mileageCacheKey(sample)
 	w.mu.Lock()
diff --git a/go/vehicle-gateway/internal/stats/daily_metric_test.go b/go/vehicle-gateway/internal/stats/daily_metric_test.go
index b9725f39..21fa936f 100644
--- a/go/vehicle-gateway/internal/stats/daily_metric_test.go
+++ b/go/vehicle-gateway/internal/stats/daily_metric_test.go
@@ -211,6 +211,33 @@ func TestWriterAppendSkipsMileageWithoutSourceIdentity(t *testing.T) {
 	}
 }
 
+func TestWriterAppendTracksSourceWithoutMileageSample(t *testing.T) {
+	exec := &recordingExec{}
+	writer := NewWriter(exec, time.FixedZone("Asia/Shanghai", 8*3600))
+	event := envelope.FrameEnvelope{
+		Protocol:       envelope.ProtocolJT808,
+		Phone:          "13307795518",
+		SourceEndpoint: "222.66.200.68:43614",
+		EventTimeMS:    time.Date(2026, 7, 8, 16, 30, 0, 0, time.FixedZone("Asia/Shanghai", 8*3600)).UnixMilli(),
+		Fields: map[string]any{
+			"jt808.location.speed_kmh": 38.5,
+		},
+	}
+
+	if err := writer.Append(context.Background(), event); err != nil {
+		t.Fatalf("Append() error = %v", err)
+	}
+	if len(exec.calls) != 1 {
+		t.Fatalf("exec calls = %d, want source only", len(exec.calls))
+	}
+	if !strings.Contains(exec.calls[0].query, "INSERT INTO vehicle_data_source") {
+		t.Fatalf("source upsert query missing: %s", exec.calls[0].query)
+	}
+	if got := exec.calls[0].args[1]; got != "222.66.200.68" {
+		t.Fatalf("source ip arg = %#v", got)
+	}
+}
+
 func TestWriterAppendDedupesRealtimeMileagePerSource(t *testing.T) {
 	exec := &recordingExec{}
 	writer := NewWriter(exec, time.FixedZone("Asia/Shanghai", 8*3600))